Fig. 1

Averaged (n = 20) time series for the body mass-normalized knee joint compression force (a) and flexion moment (b) as a result of a drop from both low and high heights. The compression force peaks for both drop heights and all three instructions are temporally aligned at approximately 0.07 s. The flexion moment peaks are temporally aligned at approximately 0.07 s for the low-stiff, high-soft, high-natural, and high-stiff conditions; while the peaks for the low-soft and low-natural conditions are temporally aligned at approximately 0.09 s